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CO,~O VIT. B12 SERUM BINDING CAPACITY 169 adult mast cells of the mesentery of rats after moderate intraperitoneal doses of the histamine liberator, compound 48/80. After larger doses, which cause disintegration of mesenteric mast cells, mitoses are found in mast cells of the subcutaneous tissue. 2) Replacement of cells after disintegration appears to be by heteroplastic differentiation of lymphocytes or undifferentiated mesenchymal cells or both.Recent studies ( 1-4) of plasma concentration and transport mechanisms of vit. B12 have included microbiological measurements of its serum in vitro binding capacity. Results have varied widely. The present investigations are concerned with estimation of Co60 vit. B12 serum binding capacity.Methods. Sera were obtained from 40 normal persons. The CoSo vit. Bl2 had a specific activity of 0.786 mc/mg. Its physiological activity was proved when 3 pg given intravenously to a patient with pernicious anemia in relapse induced a moderate reticulocyte response and clinical improvement. To 1 ml of serum was added an aliquot of CoB0 vit. B12 ranging from 1 to 500 pg. This was done either by adding the chosen amount of vitamin directly, or by making an initial concentrated solution in serum, then rediluting with more serum at once. These methods gave equal results. Specimens were prepared in duplicate, one to serve as a standard. Each was pipetted into a Visking bag. Samples were incubated at room temperature for 2 hours, then subjected to cons tan t agitation *C060 Vit. B , , was obtained from Merck & Co, Rahway, N. J. and exhaustive dialysis in cold, running tap water for 48 hours. Standards were placed in 4 ml vials at once; samples were placed in similar vials at conclusion of dialysis. Each vial was filled with concentrated sulfuric acid, dissolving the bag and allowing complete mixing within the vial. Counting was done in a well-type scintillation counter. "Bound" vit. B12 was calculated as activity retained in the bag after dialysis. Parallel studies were made with CoGoC12 and sera from 14 normal subjects. The specific activity and cobalt content of the CoS0Cl2 solution were equal to that of the radioactive vit. BI2. Continuing dialysis for 72 or 96 hours did not decrease residual activity further than the 48-hour period used. Incubation of the serum-B12 mixture for more than 2 hours prior to dialysis did not alter amount of vit. B12 bound. Dialysis for 48 hours in a reservoir of normal saline, 6% dextran in normal saline, or human plasma 50x the volume of the samples and changed at 24 hours gave the same results as exhaustive dialysis in tap water. CoB0 B12 in saline dialyzed for 48 hours in tap water showed residual activity within the Visking bag of less than 2% at any concentraby guest on July 28, 2015 ebm.sagepub.com Downloaded from

1. A survey of the incidence of abnormal hemoglobins in different racial groups distributed over the island of Puerto Rico was performed. The relation of the rate of destruction of red cells to the presence of abnormal hemoglobin patterns in the affected population was also studied. 2. The abnormal hemoglobins were classified by the difference in paper electrophoretic mobility. Fetal hemoglobin was measured by its resistance to alkaline denaturation. The red cell life span was determined by measuring the survival of erythrocytes labelled with radioactive sodium chromate. 3. A total of 2,089 inhabitants were studied. There were 1,487 white subjects and 602 Negroes. Forty-two individuals were found to harbor abnormal hemoglobins. All but one were Negroes or Negroid of African descent, and their relative numbers agreed closely with the geographical distribution of ethnic groups in the island. Abnormal hemoglobins were found in 2.01 per cent of the entire series of 2,089 persons, but in those considered Negroes or Negroids the incidence of abnormal hemoglobins was 6.8 per cent. Of the 42 persons showing abnormal hemoglobins, thirty-four or 81 per cent, had hemoglobin S; only two of these had sickle cell anemia. The incidence of the sickle cell trait among the Puerto Rican Negro population was 5.2 per cent; and the incidence of hemoglobin S disease among those harboring the trait was 5.9 per cent. Eight, or 19 per cent of the abnormal cases had hemoglobin C; only one of these had hemoglobin C disease with clinical hemolytic anemia. The incidence of the hemoglobin C trait among the Puerto Rican Negro population is 1.3 per cent; and the incidence of hemoglobin C disease among those harboring the trait may reach 12.5 per cent. 4. All 42 cases harboring abnormal hemoglobins showed very small quantities of fetal or alkali-resistant hemoglobin ranging from 0.45 per cent to 3.25 per cent, averaging 1.12 per cent. 5. The "apparent" half-life of the red blood cells was found to be 10 days in sickle cell anemia, 7 days in SC disease, 20.6 days in cases of hemoglobin SA, 18.5 days in one case of hemoglobin C disease and 21.5 days in 2 cases of the combination CA. The normal "apparent" half-life in our laboratory is 24.5 days.

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